The present invention relates to a hard disk drive, used as an auxiliary memory device in a computer, and more particularly, to an actuator latching device in a hard disk drive for maintaining an actuator in a parked position while the actuator is not in operation.
Generally, a hard disk drive used as an auxiliary memory device in a computer includes a disk which is rotated at a high speed by a spindle motor, and an actuator having a magnetic head for reading and writing data on tracks of the disk.
The actuator is rotatably installed upon a pivot. As a bobbin and coil provided at one end of the actuator move in response to operation of a voice coil motor, the magnetic head installed at the other end of the actuator moves across the surface of the disk, thereby reading data from and writing data onto the disk. The magnetic head, which is installed on a leading end of head gimbals, is displaced by an airflow generated between the magnetic head and a surface of the disk, and maintains a minute air gap between itself and the surface of the disk as the disk rotates at a high speed.
When the hard disk drive terminates operation, the actuator moves the magnetic head into a parking zone located on an inner portion of the disk. This is performed to prevent data recorded on the disk from being damaged due to undesired contact of the magnetic head with the surface of the disk.
Conventionally, hard disk drive manufacturers set a designated area on the disk where the magnetic head can be safely maintained. This area is often referred to as a parking zone, on which data is often not recorded, Or reading and writing is difficult. Typically, the parking zone is located on an inner portion of the disk. Methods for moving the actuator to the parking zone can be classified as both active and passive. A representative example of the former is a solenoid method, while an example of the latter is a magnetic latch method. The solenoid method is discussed in detail in U.S. Pat. No. 4,989,108, entitled Electro-Mechanical Latch issued to Chang on 29 Jan. 1991. This type of method has an advantage in that no significant biasing force is supplied to the actuator since the actuator latch, which operates as a mechanical pendulum-like latch, is released by applying an electrical current to the solenoid upon separation of the latch. This type of method, however, has a disadvantage in that a large number of devices for performing such functions (i.e. various mechanisms and circuits) are required, thereby occupying a large amount of space within the hard disk drive.
The magnetic latch method is disclosed in detail in U.S. Pat. No. 5,023,736, entitled Magnetic Latch For Disk Drive Actuator issued to Kelsic et al. on 11 Jun. 1991. The magnetic latch method has disadvantages in that the actuator is fixed by the force of a permanent magnet. With this type of method, a biasing force may be generated while the actuator searches for a track. Since the magnetic force is applied upon separation of the latch, the method exhibits problems in that the actuator performs unstable track searching operations. Also, upon movement of the actuator to the parking zone, the magnetic head may generate undesired noise.